Masterbatch is a concentrated way of adding colour or functional additives to a polymer. The quality of the finished part depends not only on the concentrate itself but also on dosage accuracy, resin compatibility, dispersion, temperature and feeding consistency.
Let-down ratio matters
The same percentage cannot be assumed for every masterbatch. The recommended let-down ratio depends on pigment loading, carrier resin, colour strength and the target application. Always follow the product’s technical data rather than copying a percentage from another colour.
Base resin compatibility
A colour concentrate designed for one polymer family may not behave the same way in another. Carrier compatibility influences dispersion and processing. For critical applications, validate the combination on the actual machine and product rather than relying on appearance alone.
Feeding consistency
Gravimetric dosing is typically more repeatable than manual addition, especially at low dosage. Where volumetric feeders are used, confirm that density and flow characteristics remain stable enough for the process.
Colour drift troubleshooting
| Symptom | Check first |
|---|---|
| Shade changes between shifts | Dosage, lot change and process temperature |
| Specks or streaks | Dispersion, feeding and contamination |
| Part looks dull | Surface, resin and pigment dispersion |
| Regrind changes colour | Regrind ratio and previous colour history |
Make approval repeatable
For important colours, retain a master standard and record resin grade, masterbatch grade, dosage, machine settings and the visual acceptance sample. A controlled reference reduces arguments between production, quality and customers.
Calculate from the let-down ratio
If a masterbatch is supplied for a specific let-down ratio, the operator should calculate the required concentrate relative to the base resin and confirm the feeder calibration. Guessing by volume can produce large color differences between batches.
Use a retained color standard
Keep an approved reference plaque or sample under controlled conditions. Compare production against the same reference and record the masterbatch lot. This makes supplier or process changes easier to identify.
How to use this guide
This page is designed to explain the relevant material, process, decision point or failure mode in practical terms. It is meant to support understanding, not replace a current supplier datasheet, process validation, regulatory requirement or engineering sign-off.
Typical material behavior, common process logic, defect patterns, material comparisons and practical decision framing.
Exact product specifications, grade-specific values, regulatory opinions, food-contact validation or factory-specific trials.
Before a production or commercial decision is made, check the exact grade, processing window, standards and local rules that apply to your application.